The description relates to a bipolar transistor with a reduced substrate current.
Bipolar transistors are extremely important when implementing a multiplicity of circuits, for instance for amplifying signals or in reference voltage circuits. This type of transistor forms the basis of pure bipolar semiconductor technologies but is also found in mixed technologies which combine bipolar transistors with CMOS (Complementary Metal Oxide Semiconductor) or DMOS (Double Diffused Metal Oxide Semiconductor) concepts, for instance. This makes it possible to implement a multiplicity of applications in the automobile, consumer or else industrial electronics sector, for example. The development of current and future semiconductor technologies is aimed at reducing the minimum structure sizes in order to increase the integration density of semiconductor components on a semiconductor wafer and thus save costs. The dimensions of bipolar transistors are also reduced as a result.
Within the scope of this reduction in the component dimensions, the insulation regions are closer to the collectors, in particular in the case of lateral bipolar transistors. In the case of semiconductor technologies with junction insulation, that is to say electrical insulation between adjacent semiconductor components using reverse-biased pn junctions, a distance between an emitter region of the bipolar transistor and the insulation is thus also reduced. Since the emitter and the base of the bipolar transistor form, together with the semiconductor region of the adjoining insulation, a parasitic bipolar transistor, an increased gain of this parasitic transistor is to be expected as the dimensions of the bipolar transistor are reduced further. This is due to the fact that the distance between the emitter and the insulation, which defines the width of the base, decreases as the component dimensions are reduced. However, an associated increase in the substrate current, that is to say in the collector current of the parasitic bipolar transistor, is undesirable since the substrate current can lead to undesirable driving of adjacent bipolar transistors and likewise increases the power consumption of the circuit. Such undesirable driving of adjacent bipolar transistors may result in components in the semiconductor chip being destroyed.
For these and other reasons, there is a need for the present invention.